Chemo-radiotherapy and targeted therapy are widely used as non-surgical treatments for solid tumors. Early assessment of treatment response is considered efficient and helpful to clinical management and personalized therapy.RECIST 1.1 criteria was accepted widely. Complete response (CR), partial response (PR), stable disease (SD), and progressive disease (PD) are defined in the RECIST criteria. This type of classification divides intrinsically continuous data (tumor size) into 4 bins, losing statistical power for ease of nomenclature and convenience. The 18F-FDG PET exam is based on metabolic information and considered to overcome limitations of anatomic imaging and more suitable for assessment of therapeutic response.PERCIST 1.0 proposes a series of detailed and unambiguous regulations about standardization procedures to ensure the reproducibility. Complete metabolic response (CMR), partial metabolic response (PMR), stable metabolic disease (SMD), and progressive metabolic disease (PMD) are defined in the PERCIST criteria.